In hot metal processes it is important to maintain the hot metal temperature which, in the case of the basic steel making oxygen process, permits the use of a larger percentage of low cost scrap material instead of the high cost hot metal, molten iron.
In a typical steel making process the hot metal is transported between the blast furnace and the melt facility via a hot metal conveying, or mixer, vessel which includes a rotatable submarine type ladle. The rotatable ladle is typically a refractory brick lined metal containment with a ladle mouth opening. In the basic oxygen process, a blast furnace casts the hot metal, i.e., molten iron, through the mouth opening into the ladle of the hot metal conveying vessel. The vessel is subsequently transported to the steel melting facility where the ladle is rotated to empty the hot metal contents of the vessel. The empty hot metal conveying vessel is then returned to the blast furnace and the cycle is repeated. A convention hot metal conveying vessel is described in U.S. Pat. No. 4,260,141 entitled "Centerplate Wear Liners" which is incorporated herein by reference.
It has been determined, experimentally, that the ladle refractory temperature has a significant effect on the hot metal temperature as delivered to the steel melting facility. Significant refractory temperature losses occur during the period beginning when the time the ladle is emptied at the melting facility and subsequently reused at the blast furnace. The magnitude of this loss is a function of the above time frame, the hot metal temperature prior to emptying, ambient temperature conditions, and the size of the ladle mouth opening. The refractory temperature loss is accelerated by the natural stack effect of the ladle mouth opening. It has been further noted that the rate of refractory temperature loss is greatest immediately following the emptying of the ladle at the steel melting facility.